Electrical resistance pad device



Dec. 1, 1942. w c sc 2,303,958

ELECTRICAL RESISTANCE PAD DEVICE Filed Sept. 24, 19 41 2 Sheets-Sheet lINVE N TOR W. c. SCHM/D r ATTORNEY Dec. 1, 1942. w. c sc m p'r 2,303,958

ELECTRICAL RESISTANCE PAD DEVICE Filed Sept. 24, 1941 2 Sheets-Sheet 2F/GB 'YNVE/VTOR Y WCSCHM/DT ATTORNEY Patented Dec. 1, 1942 UNlTED STATESentrant OFFICE.

Bell Telephone Laboratories,

Incorporated,

New York, N. Y., a corporation of New York Application September 24,1941, Serial No. 412,058

3 Claims.

This invention relates to electrical resistance devices and moreparticularly to resistance devices in which a plurality of resistanceelements Fig. 3 is a lower end view of the device shownin Fig. l butminus the cover on the lower end of the casing;

Fig. 4 is a view in perspective of the connector block and with aportion of the outer covering broken away to show interior portions ofthe structure;

Fig. 5 is an exploded view of the parts shown in Fig. 1;

Fig. 6 is a View of a lower portion of the casing minus the lower coverand with terminals of the resistance elements and of the terminal blockprojecting below the lower end of the casing. A strap connection isshown electrically connecting two of the terminals;

Fig. 7 is a top plan view of a blank from which the body of the casingis formed; and

Fig. 8 is a top plan view of a blank from which the lower cover isformed.

In such cases where resistance pads are required in an electrical systemit is common practice to select and assemble a plurality of resistanceelements and to electrically connect the resistance elements to form therequired resistance pads. The resistance elements may be of variousforms and values. Some of the resistance elements employed andparticularly in electrical communication systems are known as fiat typeresistances. These resistances are usually separately mounted on asupporting frame and in order to connect them to form the requiredresistance pad conductor wires are connected to the terminals of theresistances to form strap connections between the various resistanceelements. A relatively large number of strap connections are oftenrequired to interconnect the resistance elements and to connect theresistance elements to suitable terminals so that the resistanceelements will be combined to form the required resistance pad. The strapconnections and the wires leading to the terminals are rather looselyarranged and present an untidy appearance. The wiring operations arecostly and somewhat confusing.

The present invention provides a neat and compact resistance pad. Theresistance elements are enclosed in a casing particularly adapted tohold them together as a unit and which may be mounted on a suitablesupport. A connector block is provided in the unit to facilitateinterconnecting the resistance elements and to reduce the number ofwires required in making the interconnections. The terminals of theresistance elements and certain terminals of the connector block and thewires forming the interconnections are enclosed in and protected by aremovable lower cover of the casing structure.

Fig. 1 shows a resistance pad unit 9 embodying the invention andcomprising a plurality of flat type resistance elements 10, H, l2, l3,l4 and IS, the connector block l6 and the casing ll,

The casing I! is made in the form of a rectangular can comprising thebody I8, an apertured top cover l9 and a removable lower cover 20. Theparts of the casing H are made of sheet material suitable forfabrication into a substantially rigid protective casing for theresistance elements and the connector block. For the purpose ofsimplifying the description of them and not in the sense of limiting theinvention to the use of such material, it will be assumed that they aremade of sheet metal of the type commonly used in making can typecontainers. The body 18 is made from a cut-out blank 2| of the sheetmaterial as shown in Fig. 7. The blank 2! is apertured at 22 and isupwardly folded along the dotted lines 23 and 24 and upwardly along thedotted lines 25 and 26. The flaps 21 and 28 are folded upwardly alongthe respective dotted lines 29 and 30. When the blank 2| is folded alongthe lines mentioned it will be in the form of the partly formed body 3!shown in Fig. 5. Further folding along the dotted lines 23, 24, 25 and26 will bring the partly formed body 3| to the form of the body 18 shownin Figs. 1 and 6. The front wall of the casing is formed by twoparallelly arranged half sections which are partly overlapped by thefolded up flap 28. The back wall is of similar construction. After thebody IB has been formed in the manner described, the resistance elementsI0, H, l2, l3, l4 and I5 and the connector block I6 are inserted in thebody l8. The top cover I9 is then applied to the body 18. The top coverl9 has a downwardly turned.

edge flange 32 to encompass the upper end of the body l8 and is weldedor otherwise fastened along the edge flange 32 to the upper end of thebody I8.

The lower cover 20 is formed from a suitably cut-out blank 33 shown inFig. 8. The blank 33 is folded upwardly along the dotted lines 34 and 35and upwardly along the dotted lines 36 and 31. It is also foldedupwardly along the dotted lines 38 and 39 to form the partly completedlower cover 40 shown in Fig. 5. Inwardly extending embossings 4i and 42are formed in the walls 43 and 44 of the part 40 shown in Fig. 5.Further folding along the dotted lines 34, 35, 36, El, 38 and 39 willbring the partly completed lower cover shown in Fig. to the form of thelower cover 253 shown in Fig. 1. In its completed form the front wall ofthe cover 25 is cooperatively formed by the wall 45 and the two walls 46and 4?, the walls 45 and 4! overlapping a portion of the wall 45 andbeing spot-welded or otherwise secured to the wall 45 at the points 48and 39. The back wall of the lower cover 20 is formed in the same manneras the front wall. It will be seen by looking at Fig. 1 that the wall 45is about half the height of the lower cover 29 and abuts against thelower end of the body [8 when the cover 2% is applied to the body I8.The inwardly directed embossings 4| and 42 eX- tend over the upper edgeof the flap 28 to hold the lower cover 20 from accidental dislodgementfrom the body l8. A U-shaped handle 55 is secured to the lower end ofthe lower cover 20 to facilitate handling the lower cover 28. When thelower cover 29 is being applied or removed the walls 45 and 4'! will beflexed sufficiently in the region of the embossings 4i and 42 to allowpassing of the embossings 4i and 42 over the upper edge of the flaps 27and 28.

The resistances H], H, l2, [3, I4 and I5 are flat type resistancescomprising a rectangular body portion 5% and terminals 52 and areinserted in the body 58 of the casing I! so that the terminals 52 extendthrough the aperture 22 in the lower end of the body l3. as shown inFig. 6. It will be understood that the resistances comprise in each casea resistance element enclosed in the insulating body portion 5| and thatthe terminals 52 of each resistance are electrically connected to theresistance element.

The connector block l6 as shown in Fig. 4 comprises a laminatedrectangular block 53 of insulating material equipped with two sets ofterminals 54- and 55. The terminals in each set 54 and 55 are relativelylong fiat strips of conducting material and are secured to the block 53by means of eyelets or rivets 56 which project through aperturesprovided in the terminals and into the block 53. The terminals arearranged in parallel spaced relation and have end portions extendinglongitudinally outward of the block 53. The set 54 is shown ascomprising four terminals 5?, 55, 59 and E3, the projecting end portionsof which are notched at El to facilitate the connecting of wiresthereto. The set 55 is also shown as comprising four terminals 62, 63,64 and 65 with the projecting end portions apertured at 65 to facilitatethe connecting of circuit wires thereto. The terminals 51 and 58 arerather widely spaced apart on one face of the block 53 and the terminals59 and Gil are likewise spaced apart on the opposite face of the block53. The terminals 62 and 63 are located between the terminals 5? and 58and extend in parallel spaced relation therewith. The terminals 64 and65 are located between the terminals 59 and 60 and extend in parallelspaced relation therewith. Each terminal in the set is electricallyconnected by means of a conducting strap $31 to an adjacent terminal inthe other set at some convenient point along the structure of theconnector block l6. It will be seen that the projecting ends of theterminals in the set are in more closely grouped formation than theprojecting ends of the terminals in the set 54 and as shown in Figs. 1and 2 project upwardly through an aperture 58 in the top cover l9. Theterminals 53, S4 and 65 therefore project outwardly of the casingstructure and may be used as exterior terminals of the resistance pad. Acovering 59 of insulating material is provided on the connector block IEto cover all but the projecting end portions of the terminals mounted onthe block.

Supported on the top cover 59 projecting upwardly therefrom are spacedstuds 73 and H equipped with nuts 12 so that the resistance pad unit maybe supported on a supporting frame or rack, not shown. Spaced embossingsI3, 74, '15

and 76 are formed on the upper surface of the top cover I 9 to bearagainst the supporting frame or rack above-mentioned. An aperturedinsulating strip ll is provided as a closure for the aperture 5B in thetop cover 19 and to assist in maintaining the projecting ends of theterminals 62,

5 5 and 55 in required spaced relation.

The terminals 57, 58, 59 and 50 of the connector block ii: and theterminals 52 on the resistances M, H, l2, l3, I4 and 15 project throughthe aperture 22 in the casing l8 and below the lower end of the casingI? as shown in Fig. 6. These terminals may be selectively andelectrically connected by means of strap conductors 18 to form variousdesired combinations of the resistance elements and to bring theresistances into electrical connection with the terminals on theterminal block IS. The strap conductors I8 may comprise insulated wiresor other conductors suitable for the purpose and may be arranged so thatthey serve as connecting means between one or more of the resistancedevices and the connector block. In Fig. 3 which shows one of the manypossible arrangements of the strap conductors the resistances 15, ll andI2 are connected in series by means of strap conductors 78 and areelectrically connected by means of strap conductors '18 to the terminals59 and of the connector block l6. Since the terminals 59 and 60 areelectrically connected by means of conducting straps 62' the outsideterminals for this combination of resistances will be the terminals 64and proecting through the top cover l9. Again as shown in Fig. 3,resistances l3 and I5 are electrically connected by means of strapconductors l8 and other strap conductors 18 are provided to electricallyconnect this combination of resistances to the terminals 5'5 and 58 ofthe connector block 48. In this case the outside terminals for thiscombination are the terminals 52 and 63 of the connector block [6. It isobvious that various combinations of resistances may be made by suitablyconnecting the terminals thereof by means of the strap conductors l8 andthat the connector block IE facilitates the combining of the resistancesto form a required resistance pad unit.

The lower cover 20 when placed in the position shown in Fig. 1 serves incooperation with the lower end of the casing l8 and with the lower endsof the resistances enclosed in the casing as a housing for the terminals52 of the resistances, the terminals 51, 53, 59 and 63! of the connectorblock I6 and the various strap conductors l8 employed in making therequired electrical connections. The engagement of the upper ends of theWalls 45 with the bottom of the casing l8 prevents too far thrusting ofthe lower cover 26 on the casing 18. Since the inwardly extendingembossings 4i and d2 snap over and engage the upper edges of the flapportions 2! and 2B of the casing l3 accidental dislodgment of the lowercover 28 from the casing H) is prevented,

What is claimed is:

1. In an electrical resistance pad device comprising a plurality ofresistance elements stacked together in combination, a tubular casingholding said resistance elements in stacked condition, an end coverclosing one end of said casing and extending below the lower end of saidcasing to form in cooperation with said casing and the lower ends ofsaid resistance elements a lower compartment, an apertured top on saidcasing, spaced mounting studs on said top providing means for mountingsaid casing on a support, a connector block disposed between two of saidresistance elements, a set of terminal strips secured to said connectorblock and having end portions extending into said lower compartment,said end portions being electrically connected to said resistanceelements, a second set of terminal strips secured to said connectorblock and having end portions projecting through said top and conductingstraps electrically connecting terminal strips in the first set toterminal strips in said second set.

2. In an electrical resistance pad device comprising a plurality of flattype resistance elements in combination, a connector block, an aperturedcan type casing holding said resistance elements and said connectorblock in stacked condition, an apertured top cover on said casing, meanssupported on said top cover to mount said casing on a support, a set oflong strip terminals supported on said connector block and having endportions projecting outwardly through said top cover, a second set oflong strip terminals supported on said connector block and electricallyconnected to the first-mentioned set of terminals and extendingdownwardly through the lower end of said casing, terminals on saidresistance elements extending downwardly through the lower end of saidcasing, conductors electrically connecting said second set of terminalsto the terminals of said resistance elements, a removable lower cover onsaid casing enclosing said second set of terminals and the terminals ofsaid resistance elements and means on said casing and on said lowercover to pre vent accidental dislodgment of said lower cover from saidcasing.

3. In an electrical resistance pad device comprising a plurality of flattype resistances in combination, a connector block of the same gen eralform as said resistances, an apertured can type casing enclosing andholding said resistances and said connector block in stacked condition,an apertured top cover secured to the upper end of said casing, means onsaid top cover for mounting said casing on a support, two sets of longstrip terminals supported in spaced relation on said terminal block, oneof said sets having end portions extending through said top cover, theother set having downwardly projecting end portions extending throughthe lower end of said casing, conducting straps supported on saidconnector block and electrically connecting said sets of terminals,terminals on said resistances extending through the lower end of saidcasing and in spaced relation with the downwardly projecting endportions of one of said sets of long strip terminals, conductorselectrically connecting the terminals of said resistances to the set ofterminals having the downwardly projecting end portions, flap portionson the lower end of said casing, a lower cover removably supported onthe lower end of said casing and serving in cooperation with the lowerend of said casing as an enclosure for the projecting ends of one ofsaid sets of terminals, the terminals of said resistances and saidconductors, and embossings on said lower cover adapted to snap over andfrictionally engage the flap portions on said casing to preventaccidental dislodgment of said lower cover from said casing.

WILLIAM C. SCI-m/IIDT.

